Acmon Blue (Plebejus acmon) photographed at Campbell Cove on 31 May 2012. Check out the striped antennae and striped "socks"! During spring, both males and females are blue above:
Local host plants (species on which the caterpillar feeds) for Acmon Blues include legumes (e.g., Lotus spp.) and Seaside Wild Buckwheat (Eriogonum latifolium).
Here's an individual nectaring on buckwheat in the dunes in August 2010. In the second photo, look for the long tubular proboscis probing the flowers (it's between the antennae).
Acmon Blues fly almost year-round in this area. (Other species have a more restricted flight season.) Watch for these small blue butterflies (forewing is ~1 cm long) fluttering at ground level where their host plants are found.